Guard against most unintentionally ephemeral SkAutoFoo instantiations.

include/core/SkCanvas.h

Index: include/core/SkCanvas.h
diff --git a/include/core/SkCanvas.h b/include/core/SkCanvas.h
index c963edcecc85d6186beff4a29e8527d4f15be8f1..d831a5c11fe5bede41ceb3b4bc9ee0ab6b7d339c 100644
--- a/include/core/SkCanvas.h
+++ b/include/core/SkCanvas.h
@@ -1158,6 +1158,7 @@ private:
     SkCanvas*   fCanvas;
     int         fSaveCount;
 };
+#define SkAutoCanvasRestore(...) SK_REQUIRE_LOCAL_VAR(SkAutoCanvasRestore)
 
 /** Stack helper class to automatically open and close a comment block
  */
@@ -1179,5 +1180,6 @@ public:
 private:
     SkCanvas* fCanvas;
 };
+#define SkAutoCommentBlock(...) SK_REQUIRE_LOCAL_VAR(SkAutoCommentBlock)
 
 #endif